Oscillations or cycling discharges of neurons provide a
clock or impose a "tempo" for various kinds of information processing. We
recently found that olfactory bulb ET cells are endowed with spontaneous
rhythmic bursting that persists and becomes more regular in the presence of fast
synaptic blockers.Using simultaneous whole-cell recording from pairs of
juxtaglomerular (JG) neurons, we were the first to discover that membrane
potential oscillations and spontaneous bursting activity are highly correlated
in external tufted (ET) cells associated with the same glomeruli. This
synchronous activity occurs at theta frequency (1-8 Hz), the same frequency that
characterizes investigative sniffing in rodents. Therefore, synchronous ET cell
bursting may play an important role in olfactory coding and in regulating the
induction of synaptic plasticity at the first input stage of the main olfactory
bulb. In this proposal, we hypothesize that ET cells coordinate the activity of
other olfactory bulb neurons and may play a role of a pattern generator of the
olfactory bulb network. In particular, this project will assess the functional
roles of synaptic and non-synaptic interactions in establishing correlated
activity between ET cells and other neurons including interneurons and output
neurons.

We use dual patch clamp and extracellular recording techniques and
cross-correlation analysis to test the following hypotheses:

Taken together, the experiments proposed in this study will provide important,
new insights into the intrinsic synaptic organization of the glomeruli and the
role of glomerular circuitry in olfactory coding.